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Olfactory nerve Receptor 1st neuron Olfactory cells are bipolar neurons. They lie in the olfactory part of nasal mucosa and both serve as receptors as well as first neuron in olfactory pathway. The olfactory nerves,about 20 in number, represent central process of olfactory cells. They pass through cribiform plate of ethmoid bone and make synaptic glomeruli with cells of olfactory with cells of olfactory bulb.

2nd Neuron

The mitral and tufted cells in olfactory bulb give the fibers from olfactory tract and reaches primary olfactory area. Located at the primary olfactory cortex which include primary perforated substance,periamygloiad and preperiform area.

3rd Neuron

Located at primary olfactory cortex which includes the anterior perforated substance,and some small masses of grey matter.eg periamygloiad area.

4th Neuron

Arising in the primary olfactory cortex go to the secondary olfactory cortex located in uncus and anterior part of parahippocampal gyrus, tertiary olfactory cortex in posterior part of orbitofrontal cortex Some impulses from uncus travel via medial forebrain and reticular formation to dorsal nucleus of vagus and salivatory nuclei in medulla oblangata,where they may increase or decrease gastric secretion according to type of smell. Olfactory afferent pathway comprises only two neurons. The fibers reach the cerbral cortex without synapsing in any of the thalamic nuclei. Further details Www.bdc.com